1. Field of the Invention
The invention relates to ATM networks.
2. Related Art
In known ATM systems, each call is routed in a virtual circuit which is specified by the sending node. This circuit includes a plurality of ATM switches in a virtual circuit from the sending node to the receiving node. If two adjacent nodes in the virtual circuit have more than one interface connecting them, one of the plurality of interfaces must be specifically chosen and assigned to the call.
In some instances, the interface is specified by the sending node. However, when the particular interface is not specified by the sending node, the two adjacent nodes must select one of the plurality of interfaces. In known ATM systems, one interface is selected by round-robin assignment. While this method is effective to unambiguously select one of the plurality of interfaces, it has the drawback that the selected interface can be inappropriate for optimal call routing.
Accordingly, it would be desirable to provide a method and system for selecting one particular interface, which is more appropriate for optimal call routing. This advantage is achieved in an embodiment of the invention in which relative bandwidth or another characteristic of the plurality of interfaces, and in which relative size or another characteristic of the call, are examined and taken into account when one interface is specifically chosen and assigned to the call.
The invention provides a method and system for selecting one particular interface between a pair of adjacent nodes in an ATM network for assignment to a call in that network. The cell rate available on each possible interface is examined and compared with the cell rate expected for the call, and one of the interfaces is selected and assigned responsive to those cell rates.
In a first preferred embodiment, the interface is chosen which preserves the maximum remaining cell rate for future calls. In a second preferred embodiment, the interface with the highest-speed available link is chosen, so long as cell rate capacity is available on that interface for the call.